Voice logging has evolved from the use of a tape recorder coupled to a telephone line to record the conversation during a call. Today's voice logging apparatuses are far more complex. Typically such apparatuses are now implemented as circuit boards that can be inserted into the bus of a general purpose computer and have a connector for connecting to one or more telephone lines. The circuit board samples speech data from the telephone lines and to convert the sampled speech data into data that is transmitted via the bus. The assignee of the present patent application has developed an Application Program Interface (API) for such circuit boards.
Many offices have started to use shared lines for transmission of both telephone speech data and computer data, e.g. computer data sent according to the Internet Protocol. Combination of speech data and computer data is referred to as VoIP (Voice Over IP). In more advanced office systems, the line is shared for speech data and computer data from a plurality of network terminals. Voice logging apparatuses have been developed for this type of office system as well. The network interface card of a general-purpose computer is attached to the shared line to monitor the headers of data packets, to detect packets that contain speech data of a call and to write these packets to disk. There have been problems with such systems because of the vast amount of data that may pass over a shared line. These problems have been solved by using additional signal lines from the office telephone exchange to signal when telephone calls take place, and preferably also to provide call-signalling data (source telephone number etc.). Furthermore, it has been practice to store all speech packets at real time without further analysis and to reassemble the speech signals later on, when the data is retrieved for use, from the stored speech packets and the call-signalling data. Since signalling data is provided by a telephone-exchange this approach has typically limited logging to outside calls, which pass through the office exchange, without logging intra-office calls that pass via the VoIP connection but need not reach the office-telephone exchange.
Accordingly heretofore there have been two distinct voice-logging systems, for logging VoIP calls and line calls respectively. This has been found to complicate management of office voice logging.